Purification of D-glutamate-D-alanine from Bacillus subtilis will be continued. When the pure enzyme is available in sufficient quantity, we will establish its amino acid composition and the sequence of the amino acid residues around the pyridoxal phosphate at the active site of the enzyme. A search for mutants that are resistant to beta-chloro-alanine will be initiated in the hope of determining how the antibacterial agent is acting at the cellular level. The possible formation of beta-chloropyruvate from beta-chloro-alanine will be studied and the possible role of the chloroketo acid in the bacteriostatic action of beta-chloroalanine. The effect of beta-chloro-alanine on penicillin-resistant organisms will also be studied.